The invention relates to a device of a volute channel of a pump, especially the device cooperates with impellers to pumping fluid, and the total degree of volute channel surrounding the impellers is over 360 degrees.
There are two casings for the design of the flow channel of pump, which are the volute casing and the diffuser casing, and both are to recovery the partially transferred pressure energy from the high kinetic energy outputted by impellers. The application theory of the volute casing is to use that the channel area is gradually increased, that is, the diffusing channel can slow down the velocity of fluid flow and recovery partial energy; the diffuser casing adopts the angles of the diffusers to recovery the tangential kinetic energy of the high-speed fluid flow from the diffusers. The two kinds of casings are capable of reaching high efficiency. Further, they can be usually seen in the normal pumps.
For small centrifugal pump, such as small self-priming pump, small centrifugal pump, small in-line pump, etc., whose design focuses on how to save the cost to manufacture products, but the efficiency is ignored. As an example, the small centrifugal pump traditionally adopts the concentric channel of the collect casing to satisfy the goal of easy manufacturing and saving cost. However, the cross-section area of the channel is always a certain value and without the water-cut angle to less the functions of diffusing channel at the channel exit and water-cut of the volute channel so as to let the flow diffusion at the exit of the channel, and the partial fluid return back in channel. When NPSHA at the inlet of the pump is lower down, the cavitations of liquid is then increased so as to that the channel be occupied the most space of the impeller channel, hence the function to deliver liquid is almost blocked to cause the performance of pumping is highly decreased. In some prior arts, adding diffuser structure and nozzle structure to such small centrifugal pump to increase the inlet head, by using the nozzle structure to return high-pressure liquid from pump outlet, and also for better mixing of liquid and gas; the mixture also enters into the impeller with higher speed to normally deliver liquid and increase pump efficiency when pump being under the condition of low NPSHA. However, it is to directly decreasing the performance and increasing the cost, and the dimensions of pump so as to not comply with the requirement of compact size at the present marketing.
There are several prior arts related to the technology of channel of pump casing, such as U.S. Pat. Nos. 5,040,946, 5,358,380, 5,310,310, 5,234,317, 5,385,444 and 5,318,403, wherein the U.S. Pat. Nos. 5,040,946, 5,358,380 and 5,310,310 disclose the casing structure of the volute channel, which adopt to deform the outer diameter of the casing to vary with the radial dimension, (width), of the channel for enlarging the sectional area. The outer diameter of the pump casing is non-concentric because of the volute, and the axial dimensions, (depth), is not varied, further that, the total degree of the channel surrounding impeller is 360 degrees or less. The U.S. Pat. Nos. 5,234,317, 5,385,444 and 5,318,403 disclose the technology related to the pump casing structure of the channel of diffuser. Nevertheless the prior arts have not released the technology regarding the present invention.
Through many years"" experience in manufacture, devoted study, continuous research, experimental analysis, and improvement, the inventor finally proposes an invention that can reasonably and effectively improve the shortcomings of the prior arts.
The main objective of the invention is to submit a creative volute channel device of a small centrifugal pump, which has the benefits of easy manufacturing, low cost and compact size.
The second objective of the invention is to submit a volute channel device, which adopts a circular casing with concentricity to decrease cost, and designs a volute channel structure whose width and depth are gradually increased by the direction of fluid flow. The total surrounding degree of the volute channel is over 360 degrees to promote pumping efficiency.
To approach above objectives, a preferred embodiment of the volute channel device of the present invention accepts a special volute device and a throat partition to be contained in a circular casing. The volute channel device is figured as spiral to surround the exit of the impeller. Based on the direction of pumping fluid, there is a water-cut angle on the leading edge of the spiral volute channel, and the volute channel is gradually wider and deeper since the water-cut angle to enlarge the cross-section of the volute channel. The outer diameter of the volute channel is almost concentric to the inner diameter of the circular casing. The throat partition connects to the rear edge of the volute channel and extends toward the exit of the casing so as to that the throat partition is at least a partial extension of the volute channel; further, due to the extended volute channel of the throat partition overlaps with the leading edge of the volute channel structure, the total degree, surrounding the exit of the impeller, of the volute channel is over 360 degrees. Because of the circular casing, simple volute channel and throat partition, to form aforesaid structures via stamping or casting is easy and saving cost. Besides, the surrounding degree of the volute channel with increasing width and depth is in excess of 360 degrees, and cooperates with the design of the water-cut angle to ensure a better pumping efficiency but without increasing the outer diameter and height of casing.
Preferably, the position of the throat partition corresponds to the exit of the casing so as to that the exit is at the outlet of the throat partition and at the circular casing. It is to limit the fluid around the throat partition and is guided to the exit of the casing.
Preferably, the water-cut angle on the leading edge of the channel bottom plate protrudes out of the top plate and closes further to the exit of the impeller. This is not only the degree being increased, but also the height being added for better water-cut efficiency.
Preferably, there is not only one protruding hole on the channel toward the inlet of the impeller for promoting the self-priming function, by returning the high head fluid from pump outlet.
For your esteemed members of reviewing committee to further understand and recognized the structural objective and function of the invention, a detailed description incorporated with drawings is presented as follows.